A semi-direct democracy is one of several systems in which direct democracy is moderated by mandatory formal mechanisms that force a degree of deliberation or expert input into the process of setting questions that are answered by votes.

See http://en.wikipedia.org/wiki/semi-direct_democracy for general reference.

The Rank a Plank feature? is a semi-direct mechanism: the vote is not binding but does help steer attention paid certain planks. Another semi-direct mechanism is the referendum ballot that includes qualifications like knowledge-testing questions. For instance, only votes that also include 4/5 correct true/false answers on simple factual questions on the ballot might be counted, or votes that include 5/5 correct answers might count for more.